/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if ((p == nullptr) && (q == nullptr)) {
            return true;
        } else if (((p == nullptr) && (q != nullptr)) ||
                    ((p != nullptr) && (q == nullptr))) {
            return false;
        } else {
            // std::cout << p->val  << "--" << q->val<< std::endl;
            if (p->val != q->val) {
                return false;
            } else {
                return (isSameTree(p->left,  q->left)  == true) && 
                    (isSameTree(p->right, q->right) == true);
            }

        }
        

    }
};